The present invention relates generally to laser eye surgery methods and systems. More specifically, the present invention relates to methods and systems for measuring complex optical aberrations of the human eye.
Laser eye surgical systems typically employ a system that can track and measure the optical characteristics and errors of a patient's eye. One promising eye measurement system uses wavefront technology that allows the surgeon to measure and treat low order and high order aberrations in and on the patient's eye. A wavefront measurement of the eye creates a high order aberration map that permits assessment of aberrations throughout the optical pathway of the eye, e.g., both internal aberrations and aberrations on the corneal surface. The aberration information can then be used to compute a custom ablation pattern so that the surgical laser system can correct the complex aberrations in and on the patient's eye.
One exemplary wavefront technology system uses Hartmann-Shack wavefront sensors that can quantify aberrations throughout the entire optical system of the patient's eye, including first and second-order sphero-cylindrical errors, coma, and third and fourth-order aberrations related to coma, astigmatism, and spherical aberrations.
For example, as is described in U.S. Pat. No. 6,095,651, one method of analyzing the high-order aberrations in the patient's eye is through the use of a deformable mirror. The wavefront aberrations can be measured by a wavefront sensor and the deformable mirror can be deformed via control signals from the wavefront sensors to compensate for the wavefront aberration of the eye, until the error in the measured wavefront aberration reaches an asymptotic value. At that point the deformable mirror has taken an appropriate shape to provide wavefront compensation for the aberrations of the eye. Unfortunately, the adjusted shape of the deformable mirror does not directly indicate to the physician the actual aberrations of the patient's eye. Consequently, it is often required to apply a complicated calibration scheme so that the control signals used to deform the deformable mirror may be correlated with the aberrations from the patient's eye that the deformed mirror removes.
Consequently, what are needed are devices and methods which can determine the aberrations of the patient's eye, without having to employ a complicated calibration method.